Note 17 - Condensed Parent Only Financial Statements - Statements of Financial Condition (Details) - USD ($)	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Assets
Interest bearing deposits	$ 765,486	$ 6,013,890
Other assets	2,962,101	4,469,350
Total assets	300,531,696	292,836,079
Stockholders' Equity	50,710,875	52,824,366	$ 53,102,935
Total liabilities and stockholders' equity	300,531,696	292,836,079
Parent Company [Member]
Assets
Interest bearing deposits	2,434,794	6,958,943
Equity in net assets of Ottawa Savings Bank	46,828,871	44,187,104
ESOP note receivable	1,451,262	1,630,875
Other assets	(4,052)	47,444
Total assets	50,710,875	52,824,366
Stockholders' Equity	50,710,875	52,824,366
Total liabilities and stockholders' equity	$ 50,710,875	$ 52,824,366